Last week, Special Counsel Robert Mueller issued a grand jury subpoena for former Trump strategist Steve Bannon, a surprising change of tactics. Up to this point, the members of Trump’s inner circle have been allowed to have less formal interviews with Mueller’s investigators. So why the change in behavior? Aaron Blake has a few possible ideas.

As Blake notes, Bannon is probably the person close to Trump (until last week, of course) who had the least to do with anything involving Russia. Others with much closer associations in that regard have been allowed to do the interview rather than a formal grand jury interrogation. One big difference is that they can’t have their lawyer present in the grand jury proceedings. One possibility for the change is the information in the Wolff book:

Could it have anything to do with the Michael Wolff book, which quoted Bannon labeling that meeting with a Russian lawyer as being “treasonous” and as believing Mueller’s probe was “all about money laundering”? Bannon reportedly told Wolff: “The Kushner s‑‑‑ is greasy. They’re going to go right through that.” That just happens to be when the subpoena lands?

It seems possible that Mueller wants to send a signal to Bannon, who seems anxious to reconcile with Trump, that he won’t make that easy on him.

I suspect the money laundering accusation is far more important to Mueller than Bannon’s statement that the Russia meeting was treasonous. The latter is merely his opinion, and it’s wrong anyway. But I’m guessing Mueller would really like to know if Bannon has any information on money laundering, either by Kushner or Trump. I think Blake’s second suggestion is on target as well:

Another intriguing possibility is that Mueller wants to take advantage of Bannon’s tendency to spout off in real time and in an unforgiving setting. While plenty have focused on Bannon’s comments in Wolff’s book last week, this isn’t the first time he has publicly acknowledged serious errors by the Trump team with regards to Russia. During a “60 Minutes” interview back in September, you might recall, Bannon labeled Comey’s firing the single biggest mistake in modern political history. Perhaps Mueller just wants to make sure Bannon is afforded the opportunity to, well, be as candid as possible.

I have no doubt that’s true. Bannon has the same problem Trump does, verbal diarrhea. That was obvious long ago and confirmed by the Wolff book. Get him talking and he’s likely to say damn near anything, including things that are highly incriminating for himself and others. Get him in front of a grand jury with no lawyer present to advise him and he might make their entire case for them. Oh, to be a fly on the wall.

Update: Shortly after I finished writing this, it was reported that Bannon has struck a deal with Mueller to do an interview rather than be subpoenaed. That suggests that the subpoena was just to pressure him into agreeing to a more freewheeling interview than he otherwise would have. The exact parameters of how that will take place have not yet been revealed.